@perfectpol7
I pretty sure you want to setup mail server as fast as posible since
you already got registered domain.
to avoid all DNS headace you better contact your domain registra
to point your domain MX record to the server you want to install mailserver
for email server you better get several ready mail server bundle and follow
thier instruction, outside there several eg. ravencore etc. etc
however please find thier README and others instruction and read carefully
all those is the only suggestion for you, but if you want to learn hard
then build your own dns server, ask only when you stuck on doing that,
if you go to konsole mode for configuration i sure there many people
who can give a hand to you, but with webmin, ermm i not sure is there
many people use it and willing to help
ps: sorry my poor english